The present invention generally relates to hemodialysis and similar dialysis systems, including a variety of systems and methods that would make hemodialysis more efficient, easier, and/or more affordable. One aspect of the invention is generally directed to new fluid circuits for fluid flow. In one set of embodiments, a hemodialysis system may include a blood flow path and a dialysate flow path, where the dialysate flow path includes one or more of a balancing circuit, a mixing circuit, and/or a directing circuit. Preparation of dialysate by the preparation circuit, in some instances, may be decoupled from patient dialysis. In some cases, the circuits are defined, at least partially, within one or more cassettes, optionally interconnected with conduits, pumps, or the like. In one embodiment, the fluid circuit and/or the various fluid flow paths may be at least partially isolated, spatially and/or thermally, from electrical components of the hemodialysis system. In some cases, a gas supply may be provided in fluid communication with the dialysate flow path and/or the dialyzer that, when activated, is able to urge dialysate to pass through the dialyzer and urge blood in the blood flow path back to the patient. Such a system may be useful, for example, in certain emergency situations (e.g., a power failure) where it is desirable to return as much blood to the patient as possible. The hemodialysis system may also include, in another aspect of the invention, one or more fluid handling devices, such as pumps, valves, mixers, or the like, which can be actuated using a control fluid, such as air. In some cases, the control fluid may be delivered to the fluid handling devices using an external pump or other device, which may be detachable in certain instances. In one embodiment, one or more of the fluid handling devices may be generally rigid (e.g., having a spheroid shape), optionally with a diaphragm contained within the device, dividing it into first and second compartments.

Dialysis systems comprising actuators that cooperate to perform dialysis functions and sensors that cooperate to monitor dialysis functions are disclosed. According to one aspect, such a hemodialysis system comprises a user interface model layer, a therapy layer, below the user interface model layer, and a machine layer below the therapy layer. The user interface model layer is configured to manage the state of a graphical user interface and receive inputs from a graphical user interface. The therapy layer is configured to run state machines that generate therapy commands based at least in part on the inputs from the graphical user interface. The machine layer is configured to provide commands for the actuators based on the therapy commands.

Automated control mechanisms and methods for controlling fluid flow in a hemodialysis apparatus are described. The methods can involve a controller receiving information from a pressure sensor in a control chamber of a reciprocating diaphragm-based blood pump and causing the application of a time-varying pressure waveform on a diaphragm of the blood pump during a fill-stroke of the blood pump. The controller can be configured and programmed to monitor a pressure variation in the control chamber measured by the pressure sensor and to compare the measured pressure variation to a pre-determined value. Based on such comparison, the controller can initiate a procedure to pause or stop a dialysate pump of the hemodialysis apparatus if the magnitude of the measured pressure variation deviates from the pre-determined value.

A dialysis cassette includes a cassette housing having a plurality of channels fluidly coupled to a plurality of connectors and a plurality of valves disposed within the plurality of channels. The dialysis cassette also includes a pump assembly disposed within the cassette housing. The pump assembly includes a pump housing and a flexible rotor having a plurality of flexible vanes, where the flexible rotor is rotatable in either a clockwise direction or a counterclockwise direction to move a fluid through the plurality of channels.

A method of preserving a sorbent device of a dialysis system, the method comprising—after administering a first dialysis treatment at the dialysis system and before administering a second dialysis treatment at the dialysis system—circulating a fluid through the sorbent device to prevent matter within the sorbent device from solidifying and circulating the fluid through a filter coupled to an outlet of the sorbent device to remove contaminants from the fluid.

A peritoneal dialysis machine that includes a preparator as well as a cycler to form the peritoneal dialysis system. The system delivers purified water into one or more containers with different powders to create a concentrate and then moves this concentrate to a mixing bag to create the peritoneal dialysis fluid (PDF). The cycler then delivers fresh PDF to the patient and removes waste fluid via the drain outlet. A volumetric approach controls the hydraulic flow paths that introduce purified water to the powder concentrates, provide mixing of the concentrate to form the PDF and delivery of the freshly made PDF to the patient. Different configurations of hydraulic flow/pressure generators are provided in the fluid paths to provide optimization of the flow of water through the fluid system to create the correct powder concentrates and subsequent peritoneal dialysis fluid for cycling, for example being provided in a disposable cassette.

A treatment device system includes a treatment machine for performing a therapy on a patient, the treatment machine including at least one fluid conveyor and a controller, the controller having a first memory, to cause the at least one fluid conveyor to produce a therapeutic fluid by mixing purified water and at least one concentrate. The system also includes and a water purifier in fluid communication with and providing the purified water to the treatment machine. A wired or wireless control line provides two way communication between the controller of the treatment machine and the internal central controller of the water purifier, wherein the controller of the treatment machine transmits data via the control line to the internal central controller of the water purifier for control of the water purifier, the data provided based on at least one of the operator inputs received via the user interface.

A proportioning device includes a proportioning machine with a temperature-compensating conductivity sensor, a controller, and pump actuator. A fluid circuit is engageable with the pump actuator, has connections for a source of water and one or more medicament concentrates, and includes a mixing container. The controller is configured to mix contents of the mixing container at a first time and to sample fluid from the mixing container, to pass the samples from the mixing container through the temperature-compensating conductivity sensor at different points in time as the fluid flows from the mixing container. The controller is further configured to mix contents of the mixing container a second time if the conductivities differ by a predefined magnitude.

A dialysis machine (e.g., a peritoneal dialysis (PD) machine) can include a control unit configured to operate in a hybrid automated mode during a PD treatment. A processor in the control unit is configured to engage a pump during a fill phase of the PD cycle. The volume of fluid (e.g., dialysate) transferred to a patient line during the fill phase is monitored. After a dwell period, the pump is disengaged at the start of a drain phase of the PD cycle. Disengaging the pump can include: configuring valves of a disposable cassette to bypass the pump chambers of a disposable cassette; activating a bypass valve to shunt the patient line to a drain line; or moving a roller assembly of a peristaltic pump. The fluid transferred from the patient line to the drain line is monitored during the drain phase of the PD cycle.

A medicament preparation system includes a disposable cartridge with a flow path. Various sensors may be placed on the cartridge to measure qualities of the fluid flowing through the flow path. The sensors are placed in precise locations using various approaches that make manufacturing of the cartridge efficient and repeatable. A drain line that is susceptible to fouling may be preattached and various approaches are used to remove or reduce the fouling. An elastomeric contact can also be present in the medical preparation system and used in a conductivity measurement subsystem.